The present invention relates to a method of cornering identification provided for use in an anti-lock control system, wherein the rotational behavior of the vehicle wheels is measured by wheel sensors and evaluated to determine a vehicle reference speed which is used as a reference value for ascertaining the wheel slip and for braking pressure modulation, and wherein criteria for cornering identification and the direction of cornering are derived from the wheel slip.
German patent No. 34 13 738 (P 5547) discloses a circuitry for an anti-lock brake system wherein for cornering identification the slip values on the wheels of one vehicle side are added and compared with the slip sum of the wheels of the other vehicle side, and the cornering identification signal is produced as soon as the difference of the slip sums of both vehicle sides exceeds a predetermined limit value. In the brake system concerned, the braking pressure variation in individual braking pressure control channels is combined according to predefined selection criteria, such as Aselect-low@ or Aselect-high@. The selection criteria and predetermined limit values which also influence the control are changed when cornering is detected.
In an anti-lock system described in German patent application No. 21 19 590, a cornering identification signal is produced by means of a transverse acceleration measuring device, for example, a mercury switch.
Further, German patent application No. 19 65 391 discloses an anti-lock control system which determines the slip values of the individual wheels and takes them into account for the braking pressure control.
Difficulties are involved in identifying cornering and adapting anti-lock control to the different conditions prevailing during straight travel and cornering. If the control data, as is conventional practice with an anti-lock system, are produced exclusively or mainly by means of wheel sensors, the wheel slip caused by cornering must be distinguished from slip which is caused by locking tendencies or induced by the control. Principally, it would be desired to take an information about straight travel or cornering into account for the control. However, the use of a steering angle sensor, transverse acceleration sensor, or the like, which could supply such an information, is generally rejected for cost reasons. In more complex control systems, for example, in driving stability control systems (DSC, ASMS), however, it is absolutely imperative to bear the increased expenditure for sensors of the above-mentioned type.
An object of the present invention is to achieve an exact cornering identification in a simple fashion and without additional sensors, i.e., only on the basis of the data supplied by the wheel sensors.